The fruits of the orchids are basically the same in their structure within the large number of species, differ essentially only in size.
Their shape is a triple, rounded or elongated capsule, their edges correspond to the sutures of the three carpels or their midribs. With the beginning of ripeness, the fruits take on an initially yellowish color, later brownish color. They open through three or six longitudinal slits, whereby there are just as many flaps, which initially remain connected to each other by fibers and the seeds are only slowly distributed over days – dismiss. There are whirling hairs inside the capsule; they are hygroscopic, react to the change in humidity. They serve to scatter the seeds and thus to spread them further.
The seeds of the orchids are the smallest of the plant kingdom. They are produced in very large numbers, which some examples prove. It was found in the native Epipactis maculata 6200, with Cymbidium, for example 1500000, Maxillaria 1700000; the contents of a cattleya fruit will increase 3-5 Millions estimated. Because one plant can bear several fruits, there are unlikely large quantities of seeds in comparison to other plants. Their individual weight is only a few millionths of a gram and varies with their size, which is different within the species. However, all of them have a peculiarity in the absence of any nourishing tissue, which the seeds of other plants possess to a greater or lesser extent. The embryo is only made up of a net-like seed coat, the Testa, loosely surrounded. You have certain tasks, so z.B. the control of the flight after leaving the capsule, possibly also a regulation of the germination to the point in time of the most favorable conditions for the germination process. The germination capacity is relatively limited compared to the seeds of other plants; it expires about six months after the fruit has ripened. The shape and weight of the seeds are geared towards the predominantly epiphytic way of life of the orchids. The horizontally stored, Little agitated layers of air in the tropical rainforest with high humidity allow the seeds to hover slowly. He offers the guarantee, that at least some of them find suitable places on trunks or branches of trees or on rocks overgrown with moss to germinate.
Because the seeds have no nutrient tissue, they cannot germinate alone. This is why there is a community or symbiosis with microscopic root fungi. Their mycelium pervades the soil and is present everywhere, where orchids grow. The seeds have cells, in which there is more protein than in those of others. The fungal hyphae grow through these "inlet cells" into the interior of the seed that has swollen through absorption of water. They convey the absorption of organic substances, which are brought about from the outside by the entirety of the fungal network and thus serve for the first nourishment of the seedling. The fungal mycelium also remains in the plant as it develops, and always in the bark of functional root tips, where it clumps together and is digested. However, hyphae always find their way out, where then reproductive organs are formed, which begin or complete the eternal cycle of the process. The symbiosis of orchids and root fungi was discovered by the French botanist Noel Bemard at the beginning of our century, and he published his findings for the first time in the year 1904.
The germination takes place within the genera differentiated in a period of 5-20 Days. The mostly cylindrical embryos change in the course of 2-4 Weeks into top-shaped formations. After the green color already indicates the onset of chlorophyll formation, the rhizoids arise in the form of delicate threads similar to the root hairs. The first leaf systems develop a few weeks later, then the roots. The growth of the young plants now continues slowly and steadfastly over a period of several years. Determinations of the most exact kind in the tropical climate about the duration of the development up to the first bloom are not yet available. The development time extends over a period of years, varies within wide limits within the genera.